1. Field of the Invention
Embodiments of the present invention, at least as discussed herein, relate to a recording and/or reproducing apparatus, medium, and method controlling a servo, and more particularly, to an apparatus, medium, and method for controlling a write speed to vary the write speed based on a quality of areas of the disk drive.
2. Description of the Related Art
Methods for controlling the rotation speed of a disk in a disk drive may be classified into a constant linear velocity (CLV) controlling method and a constant angular velocity (CAV) controlling method.
In the CLV controlling method, a pickup uniformly maintains a linear velocity for tracking tracks, write and playback speeds are the same along inner and/or outer perimeters of a disk, and a revolution per minute (RPM) of a spindle motor rotating the disk is greatest along the inner perimeter of the disk and becomes reduced toward the outer perimeter.
In the CAV controlling method, the rotation angular velocity is uniformly maintained, an RPM of a spindle motor is maintained constant regardless of inner and outer perimeters of a disk, and the difference between write and playback speeds occurs along the inner and/outer perimeters of the disk
According to these conventional techniques, writing is performed at a relatively low speed along an inner perimeter of a disk but at a maximum speed at an outer perimeter of the disk, due to the above-described characteristics. In particular, in a disk drive into which a multilayer disk, for example, is loaded, a write speed is lowered only at the inner perimeter of the disk, as shown in FIGS. 1A and 1B, to improve the performance a spindle motor and to solve problems caused by noise generated by the spindle motor.
In general, if a disk is bent or an eccentricity exists between a central axis of a spindle motor and a central axis of a disk, the eccentricity has a bad effect on the write quality at an outer perimeter of the disk, while not having the same effect at an inner perimeter. Further, in the case of a multilayer disk, the write quality is temporarily deteriorated even when jumping between layers.
However, in the conventional techniques, to avoid these problems, the write speed is lowered only at an inner perimeter area of a disk while uniformly maintained in other areas of the disk, regardless of the quality of the disk. Thus, with this compensation, the write quality is deteriorated along an outer perimeter area of the disk due to the quality of the disk. In addition, in the case of a multilayer disk, the write quality is also greatly deteriorated during jumping between layers.